"Chris Mason announced an early alpha release of his new Btrfs
filesystem, 'after the last FS summit, I started working on a new
filesystem that maintains checksums of all file data and metadata.'
He listed the following features as 'mostly implemented': 'extent
based file storage (2^64 max file size), space efficient packing of
small files, space efficient indexed directories, dynamic inode
allocation, writable snapshots, subvolumes (separate internal
filesystem roots), checksums on data and metadata (multiple
algorithms available), very fast offline filesystem check.' He
listed the following features as yet to be implemented: 'object
level mirroring and striping, strong integration with device mapper
for multiple device support, online filesystem check, efficient
incremental backup and FS mirroring...'"